It now become standard UI pattern to display large amount of records in paginated grid layout. For example, if there is huge list of employees, application will show only 10 employees at a time. If user wants to see next set of employees, he/she can click on next button of the grid, application will pull next set of 10 employees and render on page. By showing limited number of records, you can control the amount of payload move from server to browser, saving server engagement and consumed bandwidth.
There is one common technique used by most developers to induced qualified records into a temporary table and show paginated records from there. You can learn that approach from following links:
Manual Paging, part I
http://mceahern.manilasites.com/dotnet/pagingpart1
Paging: Use ADO, getrows, or a Stored Procedure?
http://www.15seconds.com/issue/010308.htm
Is Paging with Recordsets the Best Method?
http://www.15seconds.com/issue/010607.htm
The problem with creating temp table for paginated result create substantial overheads to database, which leads to performance issue down the line.
But now in SQL Server 2005, you don’t need to create those temp table. Microsoft extent SELECT statement with new ranking function ROW_NUMBER() which return row number in result set itself.
SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNumber, OrderID, OrderDate
FROM Orders
Which will provide result something like:
RowNumber OrderID OrderDate
-------------------- ----------- -----------------------
1 10248 1996-07-04 00:00:00.000
2 10249 1996-07-05 00:00:00.000
3 10250 1996-07-08 00:00:00.000
4 10251 1996-07-08 00:00:00.000
5 10252 1996-07-09 00:00:00.000
6 10253 1996-07-10 00:00:00.000
7 10254 1996-07-11 00:00:00.000
8 10255 1996-07-12 00:00:00.000
9 10256 1996-07-15 00:00:00.000
10 10257 1996-07-16 00:00:00.000
So now you can utilize row number to get qualify records from whole table. How? Here I go
WITH Ordered AS (
SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNumber, OrderID, OrderDate
FROM Orders)
SELECT *
FROM Ordered
WHERE RowNumber BETWEEN 21 AND 30
Above SQL snippet will display records from 21st to 30th. The result will look something like this:
RowNumber OrderID OrderDate
-------------------- ----------- -----------------------
21 10268 1996-07-30 00:00:00.000
22 10269 1996-07-31 00:00:00.000
23 10270 1996-08-01 00:00:00.000
24 10271 1996-08-01 00:00:00.000
25 10272 1996-08-02 00:00:00.000
26 10273 1996-08-05 00:00:00.000
27 10274 1996-08-06 00:00:00.000
28 10275 1996-08-07 00:00:00.000
29 10276 1996-08-08 00:00:00.000
30 10277 1996-08-09 00:00:00.000
I am sure this new SELECT extension will help a lot to work on paginated resultset.
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